The present invention relates to methods of preparing amino-substituted-tetrahydroisoquinoline-sulfonamide hydroxamic acids. More particularly, the invention relates to the solid phase synthesis of substituted amino-tetrahydroisoquinoline-sulfonamide hydroxamic acids using a solid support. The invention also relates to methods of preparing combinatorial libraries of amino-substituted-tetrahydroisoquinoline-sulfonamide hydroxamic acids.
The amino-substituted-tetrahydroisoquinoline-carboxylates (amino-substituted-TIQ-carboxylates) and related compounds, such as amino-substituted-tetrahydroisoquinoline-sulfonamide hydroxamic acids (amino-substituted-TIQ-sulfonamide hydroxamic acids), are useful in numerous pharmaceutical applications. Such compounds have been useful in treatment of degenerative joint disorders, disorders of the connective tissue, ulcerations, atherosclerosis, stenosis, inflammation, carcinomatosis, anorexia, and septic shock. Thus, it is desirable to generate amino-substituted-TIQ-sulfonamide hydroxamic acids for testing as potential drug candidates. The acceleration of drug discovery has generated growing demands for efficient synthetic methods to produce therapeutic candidates. Preferably the methods are suitable for use in generating combinatorial libraries.
Schudok, U.S. Pat. No. 5,962,471, teach substituted 6- and amino-substituted-tetrahydroisoquinoline-carboxylates suitable for therapy of disorders involving increased activity of matrix-degrading metalloproteinases. Schudok teaches a method of synthesizing substituted amino-substituted-TIQ-3-(N-hydroxy)carboxamides by successively treating substituted amino-substituted-TIQ-carboxylates with ethyl chloroformate, N-methylmorpholine and O-trimethylsilylhydroxylamine. Thouin et al., Tetrahedron Letters, 41:457-460 (2000) teach the synthesis of hydroxamic acids by the nucleophilic displacement of carboxylates from oxime resins using hydroxylamine in a methanol:chloroform solution, and disclose hydroxamic acids prepared using proline, phenylalanine and alanine.
There is a need for facile and efficient methods for the synthesis of amino-substituted-TIQ-sulfonamide hydroxamic acids. It is desirable that the methods conveniently produce combinatorial libraries of compounds.
It is therefore an object of the invention to provide novel methods of preparing amino-substituted-tetrahydroisoquinoline-sulfonamide hydroxamic acids. It is also an object of the invention to provide novel methods of preparing combinatorial libraries of amino-substituted-tetrahydroisoquinoline-sulfonamide hydroxamic acids.
In accordance with one aspect of the invention, there are provided methods of preparing amino-substituted-tetrahydroisoquinoline-sulfonamide hydroxamic acids having the structure: 
wherein R1 is an alkyl, an aryl, a heterocyclic moiety, an amide, a sulfonamide, a urea, a thiourea, or an alcohol, and R2 is an aryl, a hetero-aromatic ring or a hydrocarbocycle. The methods comprise the steps of providing an orthogonally protected amino-substituted-tetrahydroisoquinoline-carboxylate attached to a solid support; attaching the R1 group to the amino-substituted of the orthogonally protected amino-substituted-tetrahydroisoquinoline-carboxylate; removing the protecting group from the orthogonally protected amino-substituted-tetrahydroisoquinoline-carboxylate to form a deprotected, R1-substituted amino-substituted-tetrahydroisoquinoline-carboxylate, reacting the deprotected, R1-substituted amino-substituted-tetrahydroisoquinoline-carboxylate with a sulfonyl chloride having the structure R2SO2C1 to form an intermediate attached to a solid support; and cleaving the intermediate from the solid support to form an amino-substituted-tetrahydroisoquinoline-sulfonamide hydroxamic acid.
In accordance with another aspect of the invention, there are provided methods of preparing amino-substituted-tetrahydroisoquinoline-sulfonamide hydroxamic acids comprising the steps of providing an orthogonally protected amino-substitutent-tetrahydroisoquinoline-carboxylate attached to a solid support; attaching a moiety selected from the group consisting of amides, sulfonamides, ureas, thioureas, alcohols, alkyls and mixtures thereof to the amino-substituent of the orthogonally protected amino-substituted-tetrahydroisoquinoline-carboxylate; removing the protecting group from the orthogonally protected amino-substituted-tetrahydroisoquinoline-carboxylate to form a deprotected amino-substituted-tetrahydroisoquinoline-carboxylate; reacting the amino-substituted-tetrahydroisoquinoline-carboxylate with a sulfonyl chloride to form an intermediate attached to a solid support; and cleaving the intermediate from the solid support to form an amino-substituted-tetrahydroisoquinoline-sulfonamide hydroxamic acid.
In accordance with yet another aspect of the invention, there are provided methods of preparing a combinatorial library of amino-substituted-tetrahydroisoquinoline sulfonamide hydroxamic acids having the structure: 
wherein R1 is alkyl, aryl, heterocyclic moiety, amide, sulfonamide, urea, thiourea, or alcohol, and R2 is aryl, hetero-aromatic ring or hydrocarbocycle. The methods comprise the step of providing a support-bound orthogonally protected amino-substituted-tetrahydroisoquinoline-carboxylate. The methods further comprise the steps of attaching a first R1 group to a first portion of the orthogonally protected amino-substituted-tetrahydroisoquinoline-carboxylate and attaching a second R1 group to a second portion of the orthogonally protected amino-substituted-tetrahydroisoquinoline carboxylate, deprotecting the first and second portions of the orthogonally protected amino-substituted-tetrahydroisoquinoline-carboxylate to form first and second deprotected amino-substituted-tetrahydroisoquinoline-carboxylates; attaching a first R2 group to the ring nitrogen of the first deprotected amino-substituted-tetrahydroisoquinoline to form a first support-bound intermediate and attaching a second R2 group to the ring nitrogen of the second deprotected amino-substituted-tetrahydroisoquinoline to form a second support-bound intermediate; and cleaving the first and second support-bound intermediates from the solid support to form first and second amino-substituted-tetrahydroisoquinoline-sulfonamide hydroxamic acids. When the first and second R1 groups are the same, then the first and second R2 groups are different, and when the first and second R2 groups are the same, then the first and second R1 groups are different. The first and second portions of the protected amino-substituted-tetrahydroisoquinoline-carboxylate may be separated prior to attachment of the R1 group, for example by partitioning the orthogonally protected amino-substituted-tetrahydroisoquinoline-carboxylate into at least a first orthogonally protected amino-substituted-tetrahydroisoquinoline-carboxylate and a second orthogonally protected-amino-substituted-tetrahydroisoquinoline-carboxylate.
In accordance with another aspect of the invention, there are provided methods of preparing an amino-substituted-tetrahydroisoquinoline-sulfonamide hydroxamic acid comprising the steps of providing an amino-substituted-tetrahydroisoquinoline intermediate attached to a solid support and having the structure: 
wherein R1 and R2 are defined above, and W represents a solid support; and cleaving the amino-substituted-tetrahydroisoquinoline intermediate from the solid support with a cleaving composition comprising NH2ON a, NH2OH and methanol to form an amino-substituted-tetrahydroisoquinoline-sulfonamide hydroxamic acid.
In accordance with yet another aspect of the invention, there are provided methods of preparing amino-substituted-tetrahydroisoquinoline-sulfonamide hydroxamic acid comprising the steps of providing amino-substituted-tetrahydroisoquinoline-carboxylate attached to a solid support; reacting the ring nitrogen of the amino-substituted-tetrahydroisoquinoline-carboxylate with a sulfonyl chloride to form an intermediate; and cleaving the intermediate from the solid support to form an amino-substituted-tetrahydroisoquinoline-sulfonamide hydroxamic acid.
The present invention provides convenient means for producing amino-tetrahydroisoquinoline-sulfonamide hydroxamic acids, and for preparing combinatorial libraries thereof. These and additional objects and advantages will be more fully apparent in view of the following description.
As used herein unless specified otherwise, xe2x80x9calkylxe2x80x9d means a hydrocarbon chain which is branched, linear or cyclic, saturated or unsaturated (but not aromatic), substituted or unsubstituted. The term xe2x80x9calkylxe2x80x9d may be used alone or as part of another word where it may be shortened to xe2x80x9calkxe2x80x9d (e.g., in alkoxy, alkacyl). Preferred linear alkyl have from one to about twenty carbon atoms, more preferably from one to about ten carbon atoms, more preferably still from one to about six carbon atoms, still more preferably from one to about four carbon atoms; most preferred are methyl or ethyl. Preferred cyclic and branched alkyl have from three to about twenty carbon atoms, more preferably from three to about ten carbon atoms, more preferably still from three to about seven carbon atoms, still more preferably from three to about five carbon atoms. Preferred cyclic alkyl have one hydrocarbon ring, but may have two, three, or more, fused or spirocycle hydrocarbon rings. Preferred alkyl include unsaturated alkyl with from one to about three double or triple bonds, preferably double bonds; more preferably they are mono-unsaturated with one double bond. Also preferred alkyl include saturated alkyl. Saturated alkyl are referred to herein as xe2x80x9calkanylxe2x80x9d. Alkyl unsaturated only with one or more double bonds (no triple bonds) are referred to herein as xe2x80x9calkenylxe2x80x9d. Alkyl unsaturated with one or more triple bonds are referred to herein as xe2x80x9calkynylxe2x80x9d. Preferred substituents of alkyl include halo, alkyl, aryl, heterocycle, hydroxy, alkoxy, aryloxy, thio, alkylthio, arylthio, amino, alkylamino, arylamino, amide, alkylamide, arylamide, formyl, alkacyl, arylacyl, carboxy and its alkyl and aryl esters and amides, sulfo, alkylsulfo, arylsulfo, sulfino, alkylsulfino, arylsulfino, phospho, alkylphospho, arylphospho, phosphino, alkylphosphino, arylphosphino, nitro, and cyano. Substituents of cycloalkyl also include cycloalkyl, aryl and heterocyclic rings which are fused or spirocycle with the initial cycloalkyl. Unsubstituted alkyl are preferred. An alkyl is bonded to another moiety at the xe2x80x9cattaching carbonxe2x80x9d of the alkyl. As used herein, xe2x80x9cprimary alkylxe2x80x9d means that the attaching carbon of the alkyl has two or three hydrogens bonded to it; xe2x80x9csecondary alkylxe2x80x9d means that the attaching carbon has one hydrogen bonded to it; and xe2x80x9ctertiary alkyl means that the attaching carbon has no hydrogens bonded to it.
As used herein, xe2x80x9cheteroatomxe2x80x9d means an atom other than carbon, preferably a nitrogen, oxygen, or sulfur atom. As used herein, xe2x80x9calkylenexe2x80x9d means an alkyl which connects two other moieties, xe2x80x9cheteroalkylenexe2x80x9d means an alkylene having one or more heteroatoms in the connecting chain.
As used herein unless specified otherwise, xe2x80x9carylxe2x80x9d means an aromatic hydrocarbon ring (or fused rings) which is substituted or unsubstituted. The term xe2x80x9carylxe2x80x9d may be used alone or as part of another word (e.g., in aryloxy, arylacyl). Preferred aryl have from six to about fourteen, preferably to about ten, carbon atoms in the aromatic ring(s), and a total of from about six to about twenty, preferably to about twelve, carbon atoms. Preferred aryl is phenyl or naphthyl; most preferred is phenyl (Ph). Preferred substituents of aryl include halo, alkyl, aryl, heterocycle, hydroxy, alkoxy, aryloxy, thio, alkylthio, arylthio, amino, alkylamino, arylamino, amide, alkylamide, arylamide, formyl, alkacyl, arylacyl, carboxy and its alkyl and aryl esters and amides, sulfo, alkylsulfo, arylsulfo, sulfino, alkylsulfino, arylsulfino, phospho, alkylphospho, arylphospho, phosphino, alkylphosphino, arylphosphino, nitro, and cyano. Substituents of aryl also include cycloalkyl and heterocyclic rings which are fused with the aryl ring or rings. Also unsubstituted aryl are preferred.
As used herein unless specified otherwise, xe2x80x9cheterocyclexe2x80x9d or xe2x80x9cheterocyclicxe2x80x9d means a saturated, unsaturated or aromatic cyclic hydrocarbon ring (or fused rings) with one or more heteroatoms in the hydrocarbon ring(s). Preferred heterocycles have from one to about six heteroatoms in the ring(s), more preferably one or two or three heteroatoms in the ring(s). Preferred heterocycles have from three to about fourteen, preferably to about ten, carbon plus heteroatoms in the ring(s), more preferably from three to about seven, more preferably still five or six, carbon plus heteroatoms in the rings(s); and a total of from three to about twenty carbon plus heteroatoms, more preferably from three to about ten, more preferably still five or six, carbon plus heteroatoms. Preferred heterocycles have one ring, but may have two, three, or more, fused rings. More preferred heterocyclic rings include those which are one ring with 5 or 6 carbon plus heteroatoms in the ring with no more than three ring heteroatoms, no more than two of which are 0 and S. Still more preferred are such 5- or 6-ring atom heterocycles with one or two ring atoms being 0 or S and the others being C; or with one, two or three ring atoms being N and the others being C. Such preferred 5- or 6-ring atom heterocycles are preferably saturated, unsaturated with one or two double bonds, or aromatic. Such preferred 5- or 6-ring atom heterocycles are preferably a single ring; or fused with a 3- to 6-ring atom hydrocarbon ring which is saturated, unsaturated with one double bond, or aromatic (phenyl); or fused with another such 5- or 6-rine atom heterocyclic ring. 1-heterocycles are unsubstituted or substituted. Preferred heterocycle substituents are the same as for alkyl.
As used herein, xe2x80x9cstrong basexe2x80x9d means an inorganic hydroxide base, alkyl-alkali metal (e.g., n-butyl lithium), alkali metal hydride (e.g., sodium hydride), alkoxide salt (e.g., sodium methoxide), alkali metal amide (e.g., lithium diisopropyl amide), and the like. As used herein, xe2x80x9csubstantial amountxe2x80x9d means a sufficient amount of a specified material such that it effects a subject invention process in a measurable way. As used herein, xe2x80x9csubstantially freexe2x80x9d means a product or other material has less than about 10%, preferably less than about 5%, more preferably less than about 2%, more preferably still less than about 1% of the indicated compound.
As used herein, xe2x80x9cnon-protic and non-oxidizing solventxe2x80x9d means a solvent that does not dissociate to provide a substantial and measurable proton concentration, and does not have substantial oxidizing potential. Protic solvents include, for example, water, methanol, ethanol, dimethylformamide and the like. Oxidizing solvents include, for example, dimethylsulfoxide, and the like.
As used herein xe2x80x9ccombinatorial libraryxe2x80x9d of compounds means a mixture of related compounds or a group of individual compounds, made substantially simultaneously by substantially the same process using a mixture of or individual related reactants to obtain related compounds. The combinational library may formed by reacting separate portions of the amino-substituted-TIQ-carboxylate with different R1 and/or R2-containing reactants. Alternatively, the combinatorial library may be formed by reacting amino-substituted-TIQ-carboxylate substrate with a mixture of R1 containing reactants or a mixture of R2-containing reactants. Finally, the combinatorial library may be formed by a method using a combination of these processes.
As used herein xe2x80x9cprotecting groupxe2x80x9d refers to a moiety attached to a functional group, such as an amine, to prevent an undesired reaction. Preferably the protecting group may be easily removed after protection of the functional group is no longer required. Suitable protecting groups include t-butyloxycarbonyl (Boc), 9-fluorenylmethoxycarbonyl (Fmoc), benzyloxycarbonyl, allyloxycarbonyl, and (trimethylsilyl)ethoxycarbonyl.
The present invention is directed to the synthesis of amino-substituted-TIQ-sulfonamide hydroxamic acids, particularly amino-substituted-TIQ-2-sulfonamide hydroxamic acids having the general structure: 
wherein R1 and R2 may be any desired moiety. Preferably R1 is alkyl, aryl, a heterocyclic moiety, amide, sulfonamide, urea, thiourea, or alcohol, and R2 is aryl, hetero-aromatic ring or hydrocarbocycle.
Synthetic methods in accordance with the present invention utilize a solid support for the synthesis of amino-tetrahydroisoquinoline-sulfonamide hydroxamic acids, preferably amino-substituted-tetrahydroisoquinoline-2-sulfonamide hydroxamic acids (amino-substituted-TIQ-2-sulfonamide hydroxamic acids). In one embodiment the solid support is a resin, preferably a polyester resin, a polyolefin resin such as polyethylene, or a polyvinyl resin such as polystyrene. As used herein, the term xe2x80x9cpolyester resinsxe2x80x9d is intended to include modified polyester resins.
Methods in accordance with the invention may comprise the steps of providing a support-bound amino-substituted-tetrahydroisoquinoline-carboxylate (amino-substituted-TIQ-carboxylate) wherein the ring nitrogen of the support-bound amino-substituted-TIQ-carboxylate has a protecting group; attaching a first moiety to the amino-substitutent group of the support-bound amino-substituted-TIQ-carboxylate; deprotecting the ring nitrogen by removal of the protecting group; reacting the ring nitrogen of the deprotected amino-substituted-TIQ-carboxylate with a sulfonyl chloride to form a support-bound intermediate; and cleaving the support-bound intermediate from the solid support to form the amino-substituted-TIQ-sulfonamide hydroxamic acid. The steps are performed at times and at temperatures sufficient for the desired reactions to occur.
The support-bound amino-substituted-TIQ-carboxylate may be formed in any suitable manner. For example, support-bound amino-substituted-carboxylate may be formed by providing a nitro-substituted-tetrahydroisoquinoline-carboxylic acid with a protecting group to form an orthogonally protected nitro-substituted-TIQ-carboxylic acid; attaching the orthogonally protected nitro-substituted-TIQ-carboxylic acid to the solid support, thereby forming carboxylate; and reducing the nitro group to form the orthogonally protected amino-substituted-TIQ-carboxylate. In another embodiment, tetrahydroisoquinoline-carboxylic acid is first bound to the support, and then nitrated in the 7-position, followed by reduction of the nitro group to an amino group.
The TIQ-carboxylate may be nitrated by any suitable manner, such as treatment with sulfuric acid and potassium nitrate or with nitronium tetrafluoroborate and acetonitrile. The nitro group may be reduced by any suitable manner, such as hydrogenation over a metal catalyst, preferably a palladium catalyst, SnCl2 in dimethyl formamide or the like. The ring nitrogen may be protected and de-protected in any suitable manner. A suitable protection method comprises reacting the TIQ-carboxylate with di-t-butyl dicarbonate, 9-fluorenylmethyl, chloroformate (Fmoc-Cl), or 9-fluorenyl methoxyl carbonyl-N-hydroxy succinimide, while a suitable deprotection method comprises treatment with a strong acid such as trifluoroacetic acid or with an amine base such as piperidine. The protecting group may be selected from the group consisting of t-butyloxycarbonyl (Boc), 9-fluorenylmethoxycarbonyl (Fmoc), benzyloxycarbonyl, allyloxycarbonyl, (trimethylsilyl)ethoxycarbonyl and mixtures thereof.
Generally, the TIQ-carboxylate is attached to the solid support by any suitable manner. In one embodiment, the TIQ carboxylic acid is mixed with the solid support in dichloromethane in the presence of 4-dimethylamino pyridine and 1,3-diisopropyl-carbodiimide. In a preferred embodiment, the TIQ-carboxylate is attached to the solid support through the acid moiety, more particularly through reaction of the support with the hydroxyl segment of the carboxylic moiety to form a carboxylate.
In one embodiment, the invention is directed to methods of preparing an amino-substituted-tetrahydroisoquinoline-sulfonamide hydroxamic acid having the structure: 
wherein R1 is alkyl, aryl, heterocyclic moiety, amide, sulfonamide, urea, thiourea, or alcohol, and le is aryl, hetero-aromatic ring or hydrocarbocycle. The methods comprise the steps of: (a) providing an orthogonally protected amino-substituted-tetrahydroisoquinoline-carboxylate wherein the orthogonally protected amino-substituted-tetrahydroisoquinoline-carboxylate is attached to a solid support; (b) attaching an R1 group to the amino substituent of the amino-substituted-tetrahydroisoquinoline-carboxylate; (c) removing the protecting group from the amino-substituted-tetrahydroisoquinoline-carboxylate; (d) reacting the deprotected, R1-substituted amino-substituted-tetrahydroisoquinoline-carboxylate with a sulfonyl chloride having the structure R2SO2Cl to form an intermediate attached to a solid support; and (e) cleaving the intermediate from the solid support to form an amino-substituted-tetrahydroisoquinoline-sulfonamnide hydroxamic acid.
While not being bound by theory, it is believed that amino-substituted-TIQ-2-sulfonamide hydroxamic acids in accordance with the invention are formed as set forth in Reaction Sequence 1 below, wherein R1 is alkyl, aryl, heterocyclic moiety, amide, sulfonamide, urea, thiourea, or alcohol; R2 is aryl, hetero-aromatic ring or hydrocarbocycle, and may comprise one or more substituents; W represents a support, such as a polystyrene resin; and Z represents a protecting group, such as t-butyloxycarbonyl (Boc), 9-fluorenylmethoxycarbonyl (Fmoc), benzyloxycarbonyl, allyloxycarbonyl, or 30 (trimethylsilyl)ethoxycarbonyl. 
The step of attaching the R1 group occurs at a temperature and for a time sufficient for the desired reaction to occur. Suitable R1 groups include amides, sulfonamides, ureas, thioureas, alcohols, alkyls, aryls, heterocyclic moieties and mixtures thereof. Any desired moieties may be used to form the R1 group, and suitable moieties include acyl halides, carboxylates, including amino acids; sulfonyl chlorides; isocyanates; isothiocyanates; epoxides; halides, including alkyl halides and aryl halides; aldehydes; and mixtures thereof. As used herein, xe2x80x9camino acidsxe2x80x9d is intended to include N-protected amino acids.
In one embodiment, the R1 group is an amide formed by reacting the amino-substituted-TIQ-carboxylate resin with an acyl chloride, generally in the presence of N N-diisopropylethylamine (DIEPA) and dichloroethane. Preferably the reaction occurs at room temperature for a period of time of about 12 hours. In another embodiment the amide is formed by activating a carboxylic acid in solution using (benzotriazol-1-yloxy)-tris(pyrrolidino)phosphonium hexafluorophosphate (PyBOP) in dimethylformamide (DMF), and adding the solution to the amino-substituted-TIQ-carboxylic resin. Preferably the reaction occurs at room temperature for a period of time of from about 1 to about 2 hours. The carboxylic acid may be an amino acid, such as a N-protected amino acid.
In another embodiment, the R1 group is a sulfonamide formed by reacting the amino-substituted-TIQ-carboxylate with a sulfonyl chloride, generally in the presence of 4-dimethylaminopyridine (DMAP) and pyridine. Preferably the step of forming the sulfonamide comprises reacting the in amino-substituted-TIQ-carboxylate with a sulfonyl chloride in the presence of about 1%, by weight, 4-dimethylaminopyrdine and pyridine at room temperature for from about 6 to about 12 hours. Generally the mole ratio of amino-substituted-TIQ-carboxylate to sulfonyl chloride is from about 1:2 to about 1:8, preferably from about 1:3 to about 1:5.
In another embodiment, the R1 group is a urea or thiourea formed by reacting the amino-substituted-TIQ-carboxylate with an isocyanate or isothiocyanate. respectively, preferably the presence of NaH in dimethylformamide. Preferably the amino-substituted-TIQ-carboxylate is reacted with an isocyanate or isothiocyanate in the presence of about 1%, by weight NaH in dimethylformamide at room temperature for about 12 hours. Generally the mole ratio of amino-TIQ-carboxylate to isocyanate or isothiocyanate is from about 1:3 to about 1:5.
In another embodiment, the R1 group is an alcohol formed by reacting the amino-substituted-TIQ-carboxylate with an epoxide in the presence of an alcohol solvent. Preferably the reaction occurs at a temperature of about 80xc2x0 C. and for a time period of about 16 hours. In one embodiment the alcohol solvent is a mixture of ethanol and isopropanol, preferably in a volume ratio of about 1:1 ethanol:isopropanol. Generally the mole ratio of amino-TIQ-carboxylate to epoxide is from about 1:3 to about 1:5.
In another embodiment, the R1 group is an alkyl formed by reacting the amino-substituted-TIQ-carboxylate with an alkyl halide, preferably an alkyl bromide. Generally the step of forming the aryl comprises reacting the amino-substituted-TIQ-carboxylate with an alkyl halide in the presence of Bu4NHSO4 and Na2CO3. In a preferred embodiment the step comprises reacting the amino-substituted-TIQ-carboxylate with an alkyl bromide in a solution comprising about 2%, by weight, Bu4NHSO4, about 5%, by weight, Na2CO3 and toluene at a temperature of about 70xc2x0 C. for a period of time of about 8 hours. Generally the mole ratio of amino-substituted-TIQ-carboxylate to alkyl halide is from about 1:2 to about 1:4.
In another embodiment, the R1 group is an alkyl formed by reductive alkylation. The amino-substituted-TIQ-carboxylate may be reacted with an aldehyde in the presence of a borane/pyridine complex. Preferably the step comprises reacting the amino-substituted-TIQ-carboxylate with an aldehyde in the presence of a borane/pyridine complex in a mixing component comprising ethanol and dimethyl formamide, more preferably the mixing solvent comprises ethanol and dimethyl formamide in a ethanol:dimethyl formamide weight ratio of about 3:1. Generally the mole ratio of amino-substituted-TIQ-carboxylate to aldehyde is from about 1:2 to about 1:4. The borane/pyridine complex is a commercially available reactant from Aldrich. A preferred R1 group may be formed by reacting the amino-substituted-TIQ-carboxylate with benzoyl chloride in the presence of N,N-diisopropylethylamine or with benzaldehyde in the presence of a borane/pyridine complex.
Suitable R2 groups include aryls, hetero-aromatic rings and hydrocarbocycles. The R2 groups may comprise one or more substituents. In one embodiment, the R2 group is an aryl comprising a substituent, a hetero-aromatic ring comprising a substituent, or a hydrocarbocycle, while in another embodiment, the R2 group is an aryl comprising a substituent, a hetero-aromatic ring comprising a substituent, or a hydrocarbocycle comprising a substituent. Suitable substituents include alkyls, aryls, alkoxys, aryloxys, OH, alkylamines, arylamines, amides, esters, carboxylates, including amino acids, NH2, acyls, NO2, CN, amidines, hydroxyl-amidines, halides, alkylthios. arylthios, SH, and non-fused or fused 5-, 6- and 7-membered heterocycles. As used herein xe2x80x9camino acidsxe2x80x9d is intended to include N-protected amino acids.
The step of attaching the R2 group occurs at a temperature and for a time sufficient for the desired reaction to occur. The R2 group may be attached to the ring nitrogen by reacting amino-substituted-TIQ-carboxylate with a sulfonyl chloride having the structure R2SO2Cl. Generally the mole ratio of amino-substituted-TIQ-carboxylate sulfonyl chloride is from about 1:2 to about 1:8, preferably from about 1:3 to about 1:5. In one embodiment, the R2 group is attached to the ring nitrogen of a support-bound amino-substituted-TIQ-carboxylate by reacting amino-substituted-TIQ-carboxylate with sulfonyl chloride, preferably in the presence of 4-dimethylaminopyridine and N,N-diisopropylethylamine. In a more preferred embodiment, the reaction occurs in the present of 1%, by weight, 4-dimethylaminopyridine (DMAP) and 1 equivalent of N,N-diisopropylethylamine (DIPEA) in dimethylformamide (DMF). The reaction may be performed at room temperature for a period of time of from about 6 to about 12 hours.
The support-bound intermediate may be cleaved to produce the substituted amino-substituted-TIQ-sulfonamide hydroxamic acid by any suitable manner. The cleavage step occurs at a temperature and for a time sufficient for cleavage to occur. A preferred cleavage step comprises treating the support-bound intermediate with a cleaving composition comprising NH2ONa, NH2OH and methanol, preferably comprising NH2ONa, NH2OH, methanol, tetrahydrofuran and N,N-diisopropylethylamine. In one embodiment, the step of cleaving the intermediate from the solid support comprises treating the intermediate with the cleaving composition in a ratio of cleaving composition to solid support of about 1.5:1.
The cleaving composition may be prepared by mixing NH2OH-HCl with NaOCH3 to form a first solution; and mixing the first solution with tetrahydrofuran and N,N-diisopropylethylamine. Generally about 1 equivalent of NH2OH-HCl is basified using about 1.5 equivalents of NaOCH3. The NaOCH3 is prepared from sodium and anhydrous methanol; the total volume of methanol used is calculated to form a 2 M concentration of NH2ONa in the resulting NH2ONa/NH2OH/methanol mixture. The NH2ONa/NH2OH/methanol mixture is then mixed with tetrahydrofuran and N,N-diisopropylethylamine in a weight ratio of about 1:10:0.5 to form the cleaving composition.
In a preferred embodiment, the cleaving step of the amino-substituted-TIQ-sulfonamide hydroxamic acid synthesis comprises the steps of agitating the intermediate attached to the solid support with the cleaving composition; obtaining a filtrate; treating the filtrate with an acidic ion exchange resin, such as DOWEX(copyright) resin; and evaporating the filtrate to obtain the amino-substituted-tetrahydroisoquinoline-sulfonamide hydroxamic acid. Preferably, the step of agitating the intermediate attached to the solid support with the cleaving composition is performed at room temperature for a period of time, for example from about 10 to about 100 minutes, preferably about 45 minutes.
If desired, the resulting substituted amino-substituted-TIQ-sulfonamide hydroxamic acid may be further isolated and/or purified by any art recognized method, such as solvent extraction and recrystallization, thin layer chromatography or high pressure liquid chromatography (HPLC).
The methods in accordance with the present invention may be conveniently used to form combinatorial libraries. In one embodiment, the invention is directed to the preparation of combinatorial libraries of amino-substituted-tetrahydroisoquinoline sulfonamide hydroxamic acids having the structure: 
wherein R1 and R2 are as defined above. One method of preparing a combinatorial library of amino-substituted--TIQ-sulfonamide hydroxamic acids comprises the steps of: (a) providing a support-bound orthogonally protected amino-substituted--tetrahydroisoquinoline-carboxylate attached to a solid support; (b) attaching a first R1 group to a first portion of support-bound orthogonally protected amino-substituted-tetrahydroisoquinoline-carboxylate and attach a second R1 group to a second portion of support-bound orthogonally protected amino-substituted-tetrahydroisoquinoline-carboxylate; (c) deprotecting the first and second portions of support-bound orthogonally protected amino-substituted-tetrahydroisoquinoline-carboxylate to form first and second deprotected amino-substituted-tetrahydroisoquinoline-carboxylates; (d) attaching a first R2 group to the ring nitrogen of the first deprotected amino-substituted-tetrahydroisoquinoline to form a first support-bound intermediate and attaching a second R2 group to the ring nitrogen of the second deprotected amino-substituted-tetrahydroisoquinoline to form a second support-bound intermediate, and (e) cleaving the first and second support-bound intermediates from the solid support to form first and second amino-substituted-tetrahydroisoquinoline-sulfonamide hydroxamic acids.
When the first and second R1 groups are the same then the first and second R2 groups are different, and when the first and second R2 groups are the same, then the first and second groups are different. Optionally, before step b, above, the orthogonally protected amino-substituted-tetrahydroisoquinoline-carboxylate may be partitioned into the first portion of orthogonally protected amino-substituted-tetrahydroisoquinoline-carboxylate and the second portion of orthogonally protected amino-substituted-tetrahydroisoquinoline-carboxylate.
Generally, the step of attaching the first and second R2 groups to the first and second deprotected amino-substituted-tetrahydroisoquinoline-carboxylate, respectively, comprises reacting a first sulfonyl chloride with the ring nitrogen of the first deprotected amino-substituted-tetrahydroisoquinoline-carboxylate to form a first support-bound intermediate and reacting a second sulfonyl chloride with the ring nitrogen of the second deprotected amino-substituted-tetrahydroisoquinoline-carboxylate to form a second intermediate. The step of cleaving the support-bound intermediates from the solid support preferably comprises treating the support-bound intermediates with a cleaving composition, preferably a cleaving composition comprising NH2ONa, NH2OH, methanol, tetrahydrofuran and N,N-diisopropylethylamine.